1. Field of the Invention
The present invention relates to a substrate on which electronic parts are mounted, specifically to a layered substrate used for a compact electronic device or the like.
2. Description of the Related Art
Recently, a compact electronic device such as a portable terminal has become smaller and thinner, and an electric circuit of the device has become more integrated. A battery used for such a device has become thinner, and so-called sheet batteries are used in Japanese Patent Application Laid-open Nos. 7-22005 and 10-126667.
Japanese Patent Application Laid-open No. 7-22005 discloses an arrangement of the thin battery within a device. The thin battery is arranged above a substrate with its end in contact with the substrate. Japanese Patent Application Laid-open No. 10-126667 discloses a thin electronic still camera in which the sheet batteries are arranged within external casings.
However, these inventions can not reduce size and thickness of devices any further.
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of a layered substrate that can reduce size and thickness of a compact electronic device.
In order to achieve the above-described object, the present invention is directed to a layered substrate, comprising: a substrate; and a sheet battery, wherein the substrate and the sheet battery form layers.
The layered substrate can reduce the thickness of an electronic device, and power for electronic parts on the substrates can be directly supplied from the battery of the layered substrate; wiring can be thus simplified.
The sheet batteries may be layered. In this case, different voltages can be directly applied from the batteries to the electronic parts on the substrates without a dc converter.
At least one substrate and at least one sheet battery on which electronic parts are mounted may form a layered substrate in layers. Two substrates on which electronic parts are mounted and at least one sheet battery sandwiched between the two substrates may form a layered substrate in layers.
The sheet batteries may be layered and connected in series.
Holes may be formed to reach electrode surfaces of at least one of the sheet batteries and wires may be inserted through the holes so that at least one power is supplied from the sheet batteries through the wires. In case the batteries are layered and connected in series, at least one voltage drawn through the wires is determined according to the electrode surfaces to which the holes are formed.
The layered substrate may be divided into areas from which kinds of electric power of different voltages are respectively drawable.
The layered substrate may further comprise ground electrode plates and at least one switch that electrically connects and disconnects the ground electrode plates. Power is supplied to electronic parts mounted on the substrates when the switch is on, and the power supply is cut when the switch is off.
The layered substrate may be arranged between an electric noise source and a circuit to prevent noise of the electric noise source from affecting the circuit.
A circuit for the digital signal processing including noise source may be printed on one of the two substrates and a circuit for analog signal processing may be printed on the other substrate so that noise of the noise source is prevented from affecting the circuit for the analog signal processing.